Progesterone concentrations during estrous cycle of dairy cows exposed to electric and magnetic fields.
ABSTRACT Sixteen multiparous nonpregnant lactating Holstein cows (each weighing 662 +/- 65 kg in 150.4 +/- 40 day of lactation) were confined to wooden metabolic cages with 12:12 h light:dark cycle during the experiment. The cows were divided into two sequences of eight cows each and exposed to electric and magnetic fields (EMF) in an exposure chamber. This chamber produced a vertical electric field of 10 kV/m and a uniform horizontal magnetic field of 30 microT at 60 Hz. One sequence was exposed for three estrous cycles of 24 to 27 days. During the first estrous cycle, the electric and magnetic fields were off; during the second estrous cycle, they were on; and during the third estrous cycle, they were off. The second sequence was also exposed for three 24 to 26 days estrous cycles, but the exposure to the fields was reversed (first estrous cycle, on; second estrous cycle, off; third estrous cycle, on). The length of each exposure period (21 to 27 days) varied according to the estrous cycle length. No differences were detected in plasma progesterone concentrations and area under the progesterone curve during estrous cycles between EMF nonexposed and exposed periods (2.28 +/- 0.17 and 2.25 +/- 0.17; and 24.5 +/- 1.9 vs. 26.4 +/- 1.9 ng/ml, respectively). However, estrous cycle length, determined by the presence of a functional corpus luteum detected by concentrations of progesterone equal to or more than 1 ng/ml plasma, was shorter in nonexposed cows than when they were exposed to EMF (22.0 +/- 0.9 vs. 25.3 +/- 1.4 days).
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ABSTRACT: Milk production is the main agricultural income in the province of Québec, and the electrical distribution network traverses the rural dairy production region. This study evaluates the hypothesis that electric and magnetic fields may affect dairy production. Sixteen multiparous nonpregnant lactating Holstein cows (weighing 662 ± 65 kg and with 150.4 ± 40 days of lactation) were confined to wooden metabolic crates during the experiment with a 12:12 h light:dark cycle. The cows were divided into two replicates of eight cows each and exposed to a vertical EF of 10 kV/m and an uniform horizontal MF of 30 μT at 60 Hz. Replicate one was exposed for three periods. Each period was represented by an estrous cycle ranging from 24 to 27 days. During the first period, the electric and magnetic fields (E&MF) were off; during the second period they were on; and during the final period, they were off. The second replicate was exposed for three periods also, but the exposure protocol was reversed (first period, on; second period, off; last period, on). Exposure to E&MF (on) resulted in an average decrease of 4.97, 13.78, and 16.39% in milk yield, fat corrected milk yield, and milk fat, respectively; and an increase of 4.75% in dry matter intake. Bioelectromagnetics 24:557–563, 2003. © 2003 Wiley-Liss, Inc.Bioelectromagnetics 11/2003; 24(8):557 - 563. · 1.86 Impact Factor
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ABSTRACT: ZUSAMMENFASSUNG: ››› Das mögliche Risikopotential hochfrequenter elektromagnetischer Felder des Mobilfunknetzes wird seit Jahren kontrovers und emotional diskutiert. Da Mobilfunksendeanlagen häufig auf landwirtschaftlich genutzen Flächen errichtet werden, stellt sich aus tier- medizinischer Sicht die Frage, ob an landwirtschaftli- chen Nutztieren in unmittelbarer Umgebung solcher Sendeanlagen Veränderungen in Gesundheit, Leistung oder Verhalten auftreten. Diese Übersichtsarbeit stellt eine Bestandsaufnahme dieses Themas dar. Neben ei- ner Reihe von Fallbeschreibungen bei Milchrindern, Schweinen und Geflügel wird die bayerische Rinder- studie diskutiert, die trotz zum Teil gravierender Män- gel einige besorgniserregende Unterschiede zwischen hoch und niedrig exponierten Betrieben zeigte, so eine Erhöhung von Missgeburten und Verhaltensänderun- gen, die zu einem Rückgang der Milchleistung führen können. Aufgrund dieser Beobachtungen planen eini- ge Arbeitsgruppen der Tierärztlichen Hochschule Han- nover eine epidemiologische Studie zur Auswirkung elektromagnetischer Felder von Mobilfunksendeanla- gen auf Leistung, Gesundheit und Verhalten von Rin- dern. Wir erwarten von dieser Studie eine weiter- führende Klärung der Frage, ob und unter welchen Be- dingungen eine Exposition in derartigen Feldern ein Risiko für landwirtschaftliche Nutztiere darstellt und zu ökonomischen Verlusten führen kann. SUMMARY: ››› The risk potential, if any, of radiofrequency (RF) electromagnetic fields as used for cellular radio sys- tems is an ongoing topic for controversial discussion. Base stations and base station antennas transmitting RF fields are often located on or near to farms, leading to the question whether farm animals in the vicinity of such stations exhibit alterations in health, productivity or behaviour. This review surveys the available infor- mations on this topic. In addition to several case reports in dairy cattle, swine and poultry, the Bavarian cow stu- dy is discussed. Despite several logistical problems of the latter study, some alarming differences evolved between farms with high and low RF field exposure, in- cluding an increase in birth defects and behavioural al- terations in exposed cows which could lead to a reduc- tion in milk production. Based on these data, scientists of the Hannover School of Veterinary Medicine plan a large epidemiological study on the effects of RF field ex- posure on milk production, behaviour and health of dairy cows. We expect that this study will help to an- swer the question if and under which circumstances en- hanced RF field exposure poses a risk for farm animals.